Only a qualified installer is allowed to connect a three-phase inverter to the power grid. It is necessary that the installer connects the various phases and the neutral conductor to the power grid in a correct and corresponding manner. However, the wiring procedure may result in wiring errors.
A method for automatically localizing single-phase ground faults in a medium-voltage grid has already been documented in DE 692 19 055 T2. This method involves measuring zero currents and generating vector sums. It also involves monitoring single currents and vector sums for phase shifts.
To detect ground faults in high-voltage grids with a resonance point grounding and an arc suppression coil, DE 10 2004 008 994 B4 proposes the use of a voltage imbalance to detect errors.
Documentation is also available (e.g., DD 053 803 B1) on testing devices that are used to connect, in pulses, a capacitor between a ground faulted phase and a protective conductor and measure the current that flows through it. This allows the devices to identify ground-faulted elements in a three-phase system. Other testing devices such as those documented in DE 10 2006 009 360 B3 are used to determine the direction of a rotary field. These devices also have a capacitor installed between the phase and neutral conductor.
DE 101 39 860 A1 documents a method for identifying a faulty connection in a three-phase device. Connection errors are identified by means of dq transformation.
For testing missing or transposed connections in Schuko sockets, DE 32 48 008 A1 proposes the use of a test circuit for connection faults.
An insulation monitoring circuit with a capacitive divider has already been documented in WO 2008 152 466 A2.